A semiconductor manufacturing apparatus has plural chambers and a substrate is conveyed into a chamber for processing at each process step. The gate valve separates between chambers. When conveying the substrate, the gate valve is opened and closed. In opening the gate valve, the pressure difference between outside and inside the chamber is made to be eliminated. The pressure inside the chamber is controlled by decompressing with a vacuum pump or supplying a gas.
If pressure difference between the inside and the outside of chambers exists in opening the gate valve, it may risk contaminating the substrate caused from scattering of particles generated inside the chamber. As stated in Patent Literature 1, an invention of a semiconductor manufacturing apparatus is disclosed. That invented apparatus prevents adhesion of particle on a wafer using airflow that occurs when the inside pressure of a reaction chamber is returned to the atmospheric pressure.